Neutral pH bars, per se, are known. Prior art neutral pH bars do not include substantial levels of hygroscopic materials, soft solids, and liquids, including water, without becoming soft or sticky with poor smears. Firm, low smear, neutral pH cleansing bars as defined herein, are believed to be novel and unexpectedly firm with good smear.
U.S. Pat. No. 3,557,006, Ferrara et al., issued Jan. 19, 1971, discloses a composite soap bar having an acid pH in use. Other background references are: U.K. Pat. Specification 513,696, Mangest, accepted Oct. 19, 1939; Jap. Pat. Application. No. 54-151410, filed Nov. 21, 1979, and published Jun. 6, 1985; and U.S. Pat. No. 4,606,839 Harding, issued Aug. 19, 1986.
Some commercial neutral pH bars are: DOVE.RTM., CARESS.RTM., and OLAY.RTM..
U.S. Pat. No. 2,988,511, Mills, issued Jun. 13, 1961, incorporated herein by reference, discloses a low smearing bar.
Bar smear, also referred to as bar sloth, is the soft solid or mush that forms at the surface of a bar when submerged in water and is regarded by consumers as messy, unattractive, and uneconomical.
However, an examination of a used personal cleansing bars in today's average bathroom will show that there is still a need to improve cleansing bar smear.
Bar smear is especially poor in neutral pH bar formulations which contain higher levels (50%.+-.10%) of synthetic surfactant.
The formation of rigid, soap curd fibers of sodium laurate is reported by L. Marton et al. in a 1940 Journal of American Chemical Society (Vol. 63, pp. 1990-1993).
Japanese Pat. J5 7030-798, Jul. 30, 1980, discloses transparent solid framed or molded soap bar.
It is an object of the present invention to produce a firm, mild, neutral pH, low smear cleansing bar that contains relatively high level of moisture in the presence of a synthetic surfactant and soft solids, such as water-soluble polyols and hydrocarbon greases.